A brush charger for static-charging a photosensitive drum by a contact method
has
a charging brush roller. The charging brush roller has a brush of a large number
of conductive fibers, and the brush is wound around a conductive support spirally.
The conductive fibers are 1.5 to 4 deniers in thickness D, are 2 mm in length L
and are planted at a density not less than 150,000 filaments/inch2,
and the thickness D and the length L of the conductive fibers meet the condition, D0.71L-;1.61.
